This invention relates to motor driven machinery and, more particularly, to motor driven turbo machinery with an internal cooling flow arrangement.
Typical motors in motor driven turbo assemblies, such as a motor driven compressor for moving air in an aircraft air conditioning system, include a rotational rotor that rotates about a motor shaft and a stator spaced radially outward of the rotational rotor. The design desire for the aircraft industry has been toward motors of smaller physical size, which provide increased power. As a result, progressively smaller motors are being driven at progressively higher rotational speeds. The combination of higher rotational speeds and smaller size results in significant heat generation, which may reduce magnetization of the rotational rotor and over a prolonged time period may ultimately result in motor or compressor failure.
One possible solution to heat generation in the motor is utilizing airflow through the space between the rotational rotor and the stator to communicate heat away from the motor. In selected conventional motor driven compressor assemblies, an internal portion of the motor is fluidly connected to an inlet port of the compressor. The compressor evacuates the internal portion of the motor during operation. Air evacuated from the motor passes through the space between the rotational rotor and the stator. The size of the space however, has decreased with the decreasing size of the motors. As a result, the airflow through the space is insufficient to provide effective thermal management of the motor.
Accordingly, there is a need for a motor driven assembly having an internal cooling flow arrangement that provides effective thermal management of a relatively small electric motor driven turbo machine.